1. Field of the Invention
The present invention relates to a circuit board. Further, the invention relates to an electrical device which contains the circuit board. Finally, the invention relates to a method of producing the electrical device.
2. Description of the Related Art
It is well-known in the art to use circuit boards in automotive instrument clusters. Such instrument clusters frequently contain several gauges to display particular quantities related to the operation of the automobile (for example, oil pressure, battery voltage, and engine RPM). Each gauge typically has a shaft which protrudes through a face plate of the instrument cluster. A pointer is mounted on the shaft. The pointer indicates, with reference to graduations on the front of the face plate and visible to the driver of the automobile, the value of the particular quantity being reported by the gauge. Each gauge further has several terminals, typically cylindrical, for electrical connections to the gauge. The terminals are typically attached to a circuit board, often an inflexible or "hard" circuit board.
A problem is encountered in the assembly of instrument clusters. The gauges are typically attached to a hard circuit board early in the assembly of an instrument cluster. Typically, the terminals of the gauges are inserted through holes in the circuit board. The terminals are then soldered to the circuit board to effect attachment and electrical connection of the gauges to the circuit board. Once the attachments to the circuit board are made, the gauges are mounted to the face plate of the instrument cluster. This mounting is typically done with screws which are inserted through holes in flanges in the gauges and which are then driven into holes in the back of the face plate. The problem encountered is in making all of the holes in the flanges of all of the gauges line up with all of the corresponding holes in the face plate. This problem is encountered due to the relative positions of all of the gauges having been fixed by the prior soldering of the gauge terminals to the circuit board.
One solution to this problem is to employ multiple circuit boards, each with holes to accommodate the terminals of some of the gauges. The relative positions of all of the gauges are therefore not fixed when the gauges are soldered to the circuit boards. This solution has several problems, including the proliferation of parts needed to build an instrument cluster and the need to provide electrical connections between the multiple circuit boards.
A second well-known solution to the problem is to mount conductive metal clips to the circuit board. One clip is provided for each terminal of each gauge. Each clip has a hole with deflectable tangs protruding into the hole. The clips allow some tolerance for misalignment of the terminals of the gauges and the holes in the clips. Each terminal of each gauge is seated in the hole in a clip and retained by tension of the deflected tangs. The use of these clips, while helping to solve the gauge alignment problem, has a number of disadvantages. For example, the clips are much more expensive than simple holes in the circuit board and the use of the clips proliferates the number of parts needed in assembly of the circuit board.
The prior art also recognizes the use of flexible material for use as the circuit board. Such material is typically a very thin plastic. A circuit board made of such flexible material does provide flexibility to help overcome the problem of misalignment of the gauges and their mounting holes. However, there are disadvantages to the use of such flexible material, including higher cost than traditional hard circuit board material and reduced reliability.
U.S. Pat. No. 5,008,496 discloses a circuit board made of thermoplastic with flexible sections and non-flexible sections. The flexible sections are thinner than the non-flexible sections. Electronic components are mounted on the non-flexible sections of the circuit board. This circuit board, while providing flexibility to a rigid circuit board, is more suited to circuit boards intended to be bent into three-dimensional shapes. Considerable flexibility is provided to allow the circuit board to be bent into a box shape, while flexibility in the two dimensions in the plane of each non-flexible section is not assured.
Given the lack of attractive solutions to the problem of assembling an instrument cluster, a hard circuit board whose gauge-mounting sections can be moved to allow the mounting of the gauges to the face plate of the instrument cluster would provide significant advantages over the prior art.